Two people have been arrested on suspicion of the murder of missing teenager Becky Watts.

A 28 year-old man and 21 year-old woman were arrested on suspicion of kidnap on Saturday and further arrested earlier, Avon and Somerset Police said.

The 16-year-old was last seen at her home in the St George area of Bristol on 19 February.

Earlier two forensics vans were seen leaving with several brown evidence bags from Becky's home.

'Critical significance'

Three homes in the city have been searched as part of the investigation, the force said.

No further details about the two people arrested were released by police but they said there was "sufficient information" to justify their arrests.

They can be detained for a further 36 hours without charge.

Det Supt Mike Courtiour from Avon and Somerset Police said they were at a "critical stage" of the investigation.

He added: "This is a very sensitive investigation and I am not in a position to give you any further information or the identity of those in custody,

"In the meantime, our search for Becky continues unabated."

Mr Courtiour also said additional officers from Wiltshire, Gloucestershire and Devon and Cornwall and police dogs from South Wales Police had been drafted in.

"We have family liaison officers who have spoken to the immediate family this afternoon and I understand the family are very distraught," he added.

Searches are continuing at houses in Wilton Close, Southmead, at Cotton Mill Lane, Barton Hill, and at her family home in Crown Hill, St George.

Image copyrightAVON AND SOMERSET POLICEImage caption
Police want more information on the whereabouts of a black Vauxhall Zafira between the 19 and 23 February

Further searches are also taking place off Wharf Road in Fishponds and at Trym Valley, near Southmead. Later on Monday, another search began in Badock's Wood, near Southmead and police divers also began searching Henleaze Lake, Bristol where Henleaze Swimming Club is based.

Police are also trying to trace sightings of a black Vauxhall Zafira with the registration plate HY06 HYA, which neighbours say officers examined and took from in front of the house in Southmead.

Police say the "critical time" on which they need information about the car is from the morning of Thursday 19 February to the following Monday.

They also want to talk to the vehicle's previous owners.

During a press conference, police said they could not comment on the current ownership of the car but that it was of "critical significance".

Image caption
A second police tent has been erected at the front of a house in Barton Hill

Image caption
Police searched an area near Southmead called Badock's Wood

Image caption
A blue tent has been erected in the back garden of the Barton Hill home

Forensics officers arrived at the Barton Hill address at about 11:00 GMT.

Aerial pictures revealed that a blue tent had been erected in the back garden of the home.

The BBC's Jon Kay said officers could be seen using ladders to access the house in Southmead.

Timeline of Becky's disappearance

Friday 20 February - Becky is reported missing at 16:00 after her family says she was last seen at her home the previous morning

Tuesday 24 February - Her father Darren Galsworthy and grandmother Pat Watts appeal for Becky to get in touch. Meanwhile, the nearby nature reserve at Troopers Hill is searched

Wednesday 25 February - Becky's home in Crown Hill, St George, is searched

Saturday 28 February - Two people are arrested in connection with Becky's disappearance

Monday 2 March - A 28-year-old man and a 21-year-old woman held since Saturday are further arrested on suspicion of the murder and kidnap of Becky